Desert Tank Solutions?

So I bought a 3.1 gal. desert tank for my 07 YZ 450 last year. It's an Acerbis clear tank and I like it because there's no need to stop to check fuel level and it holds quite a bit more fuel than my stock tank. The tank extends far forward and has two bolt holes on either side to bolt to the radiator supports, so it takes place of the plastic shrouds with a stock set-up. With the forward extension there is a small problem... there's about a quarter of a gallon worth of fuel that I can't even access (unless I'm riding a wheelie) because it sits below the petcock. So I removed the petcock and did a little modification and ran two vinyl lines to reach the deep reaches of the tank. My question is will I be able to draw the remaining fuel up and then down to the carburetor. Some people think that because this is gravity feed that it won't work. I wonder if there's enough vacuum to make this work like i think it should. If anyone has anything to add, please do. I guess I could always find out through trial and error.

Vacume no. Well there should be siphon, the carbs is lower than the lowest part of the tank so gravity will pull that while sitting still but I have a feeling that while riding and going over bumps when the needle and seat opens and your down to your portion of the tank below petcock it will loose its prime. As long as the lines are not trash its not going to hurt to try. The real fix would be to add another petcock.

IF the flow from the upward looped lines manages to establish a bubble-free line of flow to the carb before the level drops that low, it will then work as a siphon does and pull fuel from the low spot. If the stream is interrupted by even a small amount of air through vibration, etc., the siphon will be "broken", and it will drain no farther than the highest point in the lines you added.

Thanks for the insight. I did think about adding another petcock valve, but I was having trouble finding a suitable place to mount one on the tank fins. I guess I'll try this set-up and see how it goes. Even though I can't use every bit of fuel in the tank I can still travel over 70 miles on a fill and that is very acceptable.

possibly join the bottoms of each side at there lowest point, then tee it into the fuel line below the petcock, with a valve before the last connect prior to the petcock?

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